1. Field of the Invention
The field of this invention is depth adjusting systems for power tools. More particularly the field is depth adjusting systems for screw guns in which part of the system is easily removable from the screw gun to gain access to the spindle and screwdriving bit, and the system retains its depth setting when it is replaced on the screw gun.
2. Description of Related Art
U.S. Pat. No. 4,647,260 to O'Hara et al. and U.S. Pat. No. 5,341,704 to Klemm disclose depth adjusting systems for screw guns.
The O'Hara et al. patent discloses a two piece depth adjusting system comprising an adjustment collar (26, FIG. 2) and a depth locator (28). The adjustment collar releasably attaches to the nose portion (24) of the screw gun. The depth locator (28) engages the adjustment collar (26) through a screw thread arrangement. When attached to the nose portion (24), the adjustment collar (26) is rotated to adjust the axial position of the depth locator (28). The depth locator (28) is prevented from rotating relative to the nose portion (24) so that when the adjustment collar (26) rotates, the depth locator (28) is in turn driven axially through the screw thread arrangement. Indexing means are also provided between the nose portion (24) and the adjusting collar (26) to retain the adjusting collar (26) in a predetermined angular position relative to the nose portion (24) and thus also retain the depth setting of the depth locator (28). However, when the adjusting collar (26) is removed from the nose portion (24), the indexing means no longer retains the angular position of the adjusting collar (26). When a user removes the adjusting collar (26) and the depth locator (28) to, for example, change the screwdriving bit, the depth setting may be lost and will have to be reset when the adjusting collar (26) and depth locator (28) are replaced on the screw gun.
The Klemm patent discloses a two piece depth adjusting system comprising a sleeve (94, FIG. 7) and a depth locator (76). The sleeve (94) is releasably attached to the gear case of the tool. A groove (40, FIG. 2) on the gear case holds a resilient split retaining ring (42). A flange (98) on the sleeve (94) engages and moves over the retaining ring (42) with an audible snap when sleeve (94) is attached to the gear case. The sleeve (94) may be detached by pulling it axially away from the gear case. In the commercial embodiment of the Klemm patent, the force required to detach the sleeve (94) varies and is sometimes excessive when the flange (98) “hangs up” on the retaining ring (42).
Once attached, the sleeve (94) does not rotate or move axially relative to the tool. The depth locator (76) engages the sleeve (94) through a screw thread arrangement. Rotation of the depth locator (76) by the user causes the depth locator (76) to be driven axially by the screw thread arrangement to adjust the depth setting. An indexing means between the sleeve (94) and the depth locator (76) retains the angular position of the depth locator (76) relative to the sleeve (94) and thus maintains the depth setting. Although the indexing means functions regardless of whether the sleeve (94) is attached to the gear case, in order to adjust the depth locator (76), the user must manually turn the depth locator (76) itself. This can be awkward because the radius of the depth locator (76) is relatively small so that turning the locator (76) is not ergonomically comfortable.